XI 



PHYLUM ARTHROPODA 



567 



foot " to keep the cavity of the carapace free from foreign 

 bodies. There are eight thoracic appendages (&//), all of them leaf- 

 like, and recalling those of Apus. The first four abdominal appen- 

 dages (p l p 4 ) are large biramous swimming-feet, like those of 

 Copepods ; the fifth and sixth (p 5 , p ( .) are small and uniramous. 



Tfi:3 Ab.l 



FIG. 465. Paranaspides lacustris, ;<4. ai, antennules ; a 2 , antennae; Ab.l, first 

 abdominal segment ; ep, epipodites or gills on the thoracic legs ; md, mandible ; Pl.l, first 

 abdominal appendage ; T, telson ; Th.8, eighth free thoracic segment ; U, uropod. (After 

 Geoffrey Smith.) 



The Syncarida (Anaspidacca) (Fig. 465) are small, shrimp-like, 

 fresh-water Crustaceans, which, though resembling the rest of the 

 Malacostraca (Eumalacostraca) in the presence of only six segments 

 in the abdomen and the absence of caudal styles, differ from them in 



FIG. 466. Mysis oculata. 



end. endopodite ; ex. exopodite ; ot. otocyst ; p, brood-pouch. 

 (After Gerstaecker.) 



the possession of a combination of features which connect them more 

 closely with certain fossil forms of Carboniferous age. Thus there 

 is no carapace, the thoracic appendages are provided with slender 

 respiratory exopodites, and bear a double series of epipodites or 



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